1. Field of the Invention
This invention relates to devices and methods for generating light, and more particularly to electrodeless plasma lamps energized by microwave radiation. Rather than using a waveguide with an air-filled resonant cavity, embodiments of the invention use a waveguide having a body including at least one dielectric material with a dielectric constant greater than approximately 2. Such dielectric materials include solid materials such as ceramics, and liquid materials such as silicone oil. The body is integrated with at least one lamp chamber containing a bulb.
2. Description of the Related Art
Electrodeless plasma lamps provide point-like, bright, white light sources. Because electrodes are not used, they often have longer useful lifetimes than other lamps. Electrodeless lamps wherein microwave energy is directed into an air-filled waveguide enclosing or otherwise coupled to a bulb containing a mixture of substances that when ignited form a light-emitting plasma include: European Pat. App. EP 0 035 898 to Yoshizawa et al.; and U.S. Pat. No. 4,954,755 to Lynch et al., U.S. Pat. No. 4,975,625 to Lynch et al., U.S. Pat. No. 4,978,891 to Ury et al., U.S. Pat. No. 5,021,704 to Walter et al., U.S. Pat. No. 5,448,135 to Simpson, U.S. Pat. No. 5,594,303 to Simpson, U.S. Pat. No. 5,841,242 to Simpson et al., U.S. Pat. No. 5,910,710 to Simpson, and U.S. Pat. No. 6,031,333 to Simpson. U.S. Pat. No. 6,617,806 B2 to Kirkpatrick et al. discloses a plasma lamp having a cylindrical, metallic resonant cavity containing solid dielectric material allowing a reduction in cavity size.